Gas lift valves are an integral part of the tubing in gas lifted wells. Many operators use tubing with premium threads for these wells. Additional safety equipment, including the packer and the downhole safety valve, has been subjected to a program intended to prove its capabilities as a safety device. This is not the case with standard gas lift valves, developed and delivered according to the governing standard, ISO 17078-2. On the contrary, this standard states that the valves are only intended to be a flow check and not a pressure safety device. This paper discusses the development of a new validation standard, where the intention is to prove the equipment's safety capacity, as well as new equipment developed to meet these challenges. Introduction Most operating companies design their wells according to external or internal regulations with respect to safety equipment and safety levels. Each component needs to meet material standards and specific equipment standards. The standards will also describe production requirements as well as acceptance testing procedures for the equipment in question. New equipment typically has to be qualified to a certain validation procedure described in a standard issued by an external standards organization and often to additional internal company requirements. Barrier Philosophy The safety philosophy of preventing uncontrolled release of hydrocarbons is often referred to as barrier philosophy. The barrier philosophy for a given well typically depends on region, nationality and operating company. The Norsok D-10 is an example of a standard describing elements preventing hydrocarbon or pressure release to the atmosphere and it defines well barriers as; " Well barriers are envelopes of one or several dependent well barrier elements preventing fluids or gases from flowing unintentionally from the formation, into another formation or to surface. The well barrier(s) shall be defined prior to commencement of an activity or operation by description of the required well barrier elements to be in place and specific acceptance criteria.??
Required safety factors in pressure activated perforating systems have in practice limited the number of independent gun sections on one run to at the most two. The Halliburton Select Fire System eliminates this limitation by allowing as many gun sections as desired to be independently activated by applying the same level of activation pressure each time. Potential cost savings derived from the system can be divided into two groups; reduced operational time due to reduced number of runs, and greater versatility of the perforating system, allowing for new approaches in planning and execution of the perforating operations. The paper reviews three different cases were the system has been used in the Greater Ekofisk Area. Introduction Pressure activated perforating systems usually rely on applying either annular or tubing pressure to shear a set of shear pins, releasing a mechanism to mechanically impact a detonator, thus activating the detonation train through the perforating system. The activation pressure window constraints for a given system are determined by hydrostatic pressure, safety factors, pressure testing of other equipment, operational pressure of other equipment, limiting casing pressure etc. This can in many situations make it difficult to find a satisfactory pressure window to activate even one pressure activated perforating system. The Greater Ekofisk Area. The Greater Ekofisk Area is located in the southern region of the Norwegian sector in the North Sea. The area includes most of the chalk fields located in the North Sea. The included fields are Ekofisk West Ekofisk, Albuskjell, Tor and Ekofisk. Some fields in the area have porosity exceeding 50%. However, the average porosity in the Ekofisk field is about 30-32% with a matrix permeability of 1 mD and a total permeability of 150 mD included the natural fractures in the reservoir rock. Most Ekofisk Area wells require acid fracturing to improve production. System Description The Halliburton Select Fire (HSF) System uses standard perforating guns and firing heads In addition to the newly developed equipment. The firing heads are protected in atmospheric chambers until they are ready for detonation. Activation of the system is accomplished by leading either tubing or annulus pressure through a control line to the gun sections. P. 449
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper describes a system developed for live well perforating and presents several case histories of its usage. The system has currently been used on 13 jobs on the Statfjord field. A total of 2106 m has been perforated, and the longest interval in one run has been 277 m in this particular field. The system has been used both for initial perforation on new wells and reperforation in live wells or in combination with zone isolation. Both injectors and producers have been perforated using this system.An optimum perforating strategy can have significant impact on the economy of a well. During the past few years, techniques to perforate wells without having to use kill fluid have been developed. This reduced the cost and the problems that can occur as a result of kill the well. Kill fluid can not only affect the productivity of the wells, but may also create problems when produced back to the hydrocarbon process equipment. In addition, it has been noted that a higher and more stable sand free production rate will be obtained if the entire interval is perforated simultaneously. 1 Perforating underbalanced allows the debris in the perforating tunnel to be cleaned more easily. 2 If the well does not have to be killed, considerably less formation damage will occur, and the costs of kill fluid, lifting the well, and handling of the returned kill fluid are also eliminated.This paper describes a new live well perforating method deployed with a hydraulic workover unit, that allows long intervals to be perforated in wells with complicated well trajectories
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